The busiest airport in the United States in 2025, as well as the rest of the world in most other years since the turn of the millennium, has been Hartsfield-Jackson Atlanta International Airport (ATL). This facility, which offers nonstop services to destinations all across the globe, has long been a principal hub for the US-based legacy carrier 
Delta Air Lines (NYSE: DAL). A fortress hub that serves as the principal global linchpin of the Delta Air Lines network, this facility has long been one of the biggest and most valuable assets in Delta’s operational portfolio. Almost no carrier comes close to matching Delta’s passenger traffic through Atlanta, and the facility’s status as a fortress hub for the airline is unlikely to change anytime soon.
With dozens of gates, the airport is spread across multiple concourses, serving destinations nearby and far away. This allows the airline to offer exceptional connectivity and provide a hub for travelers from all across the globe. As a result, legacy airlines across the SkyTeam alliance, of which Delta is a key member, use the airport as a base of operations for flights to and from the United States. We analyze the growth and strategic value that the US’s busiest airport offers to Delta Air Lines.
A Brief Overview Of Hartsfield-Jackson Atlanta International Airport (ATL)
Hartsfield-Jackson Atlanta International Airport is the principal gateway to the Atlanta metropolitan area, and it is located around 10 miles south of the city’s downtown. The facility is named for former mayors William B. Hartsfield and Maynard Jackson, both of whom led the city through various periods of development. The airport has led the world in passenger traffic every year since 1998 except for 2020, when it rebounded to 108.1 million passengers in 2024. The airport is also the world’s leader in terms of aircraft movements, and the facility anchors Delta’s global operations, serving as the airline’s headquarters and the primary base for its Technical Operations Center.
The airport stands out as the world’s largest single-airline hub, with flights offered to more than 200 global destinations. Frontier Airlines, Southwest Airlines, and Spirit Airlines also maintain operating bases at the facility, with ATL offering international service to destinations across North America, Latin America, Europe, Africa, the Middle East, and East Asia. Geographically, Atlanta’s primary airport spans more than 4,700 acres across unincorporated portions of Clayton County, with some areas located inside the city of Atlanta’s boundaries.
The airport is well-connected to the surrounding metropolitan area by the city’s Metropolitan Atlanta Rapid Transit Authority (MARTA), which offers service on both its Red and Gold lines. This facilitates rapid access to the city’s downtown. Airside, five parallel runways support high-capacity operations, with the longest of these being capable of handling the mammoth Airbus A380. This expansive runway system, which is paired with extensive terminal infrastructure and banked hub scheduling, underpins the hub’s efficiency and resilience.
A Look At The History Of Hartsfield-Jackson Airport
Hartsfield-Jackson Airport’s story begins in 1924 on the site of a former racetrack, where an airfield originally operated under a rent-free city lease. Early services were operated by Eastern Air Lines and later by Delta Air Lines, which had turned the facility into a busy hub by the time 1930 arrived. World War II saw joint military use and record operations. The facility was later renamed as Atlanta Municipal Airport in 1942, and it opened a landmark $21 million terminal in 1961, shortly before the airport was rebranded by Mayor William B Hartsfield.
Explosive growth led to the construction of today’s complex, which was opened in 1980 under the supervision of Mayor Maynard Jackson, with Concourses A, B, C, D, T, and later E opening shortly after. The International Terminal opened in 2012. Capacity continued to rise as parallel runways expanded, including a fifth runway, which was built over I-285 in 2006. The nation’s tallest control tower also opened at the facility shortly after.
Today, the airport remains a dominant facility for global air traffic, and it is a crucial linchpin in the connecting network of Delta Air Lines. A carrier that focuses primarily on connecting passengers to destinations throughout its global network, Delta Air Lines is especially reliant on this facility, as it offers exceptional connectivity for passengers looking to travel to destinations all across the globe. The airport is a core transatlantic gateway for the carrier, and is also the linchpin of Delta’s Latin American network.
A Brief Look At Operations At Atlanta Hartsfield-Jackson Airport Today
Delta Air Lines and Eastern Airlines dominated the 1970s, and, following deregulation that took hold of the industry, Eastern Airlines collapsed. Delta Air Lines consolidated its hub at the airport, and AirTran’s rise at the facility quickly came to a close once Southwest Airlines acquired the carrier in 2014. This brings us up to date on the way the airline currently dominates the market in Atlanta, operating services worldwide.
Starting in 2015, low-cost carriers, including Frontier Airlines and Spirit Airlines began expanding their presence at the airport. More options equate to cheaper fares for customers, ensuring that even those traveling on a budget from the Atlanta area will have something to choose from. International carriers have continued to add destinations to the airport. Some international carriers like Virgin Atlantic, Turkish Airlines, 
Qatar Airways, WestJet and Copa Airlines have become bigger players at the airport.
Some more recent additions to the airport’s operational network include services from Air Canada, Ethiopian Airlines, LATAM Peru, Aeromexico, Scandinavian Airlines System (SAS), and Etihad Airways. The extensive ground transportation network at the airport, including the MARTA rail system which was introduced in 1988, has made it an easy place for passengers to transfer through. If frictions occur, passengers have a variety of hotel options to choose from for an unintended overnight layover.
A Deeper Look At The Competitive Landscape At The Airport
Atlanta is a classic fortress mega-hub with a fairly asymmetric competitive landscape. Delta Air Lines accounts for around 73.7% of passenger traffic, and its fully owned regional subsidiary Endeavor Air adds another 4.3% to the mix, bringing the airline’s overall share up as high as 78%. This dominance compounds the airline’s preexisting hub economics, including banked waves and unrivaled schedule breadth, with more than 1,000 daily flights. The airline also uses the facility to bolster the strength of its SkyMiles loyalty program, corporate contracts and scale of its TechOps operations. Unit costs are lower and that supports reliability.
Competitor market shares are extremely fragmented. Southwest Airlines remains the second-largest player at the facility with a market share of around 7.1%, but its point-to-point strategy limits its interest in building a larger hub at the airport. The airline had a legacy presence at the facility as a result of its acquisition of AirTran. Frontier Airlines and Spirit Airlines both stimulate origin and destination traffic with their lower fares, but a combined market share of lower than 8% limits connectivity and network strength, making them an illogical choice for business travelers, according to data from the Bureau of Transportation Statistics.
|
Airline: |
ATL Market Share: |
|---|---|
|
Delta Air Lines (including Endeavor Air) |
78% |
|
Southwest Airlines |
7.1% |
|
Frontier Airlines |
4.28% |
American Airlines and United Airlines both have relatively limited hub presences at the airport, meaning that their presence is mostly limited to flights to and from their major hubs. Absolute volumes remain very small for international carriers as well, which are mostly outsized by Delta’s transatlantic portfolio.
Why Does Atlanta Matter So Much To Delta Air Lines?
Atlanta remains the crown jewel hub of Delta’s large global network, and the facility remains the company’s home. It anchors the economics of the airline’s entire network. The company sits at the crossroads of multiple different air traffic patterns, making it ideal for connecting passengers traveling to South America and Europe. The airline operates roughly 1,000 daily flights, providing the airline with unmatched frequency and connectivity.
The airline’s loyalty program, SkyMiles, also centers around Atlanta operations, with flagship lounges at the airport. The facility’s co-location of headquarters for Delta TechOps, which is a major cash-generating outsourcer of revenue and maintenance services, provides an even further source of value for the airline.
The airport’s fortress-hub scale lets Delta Air Lines deploy its aircraft and crews flexibly, smoothing seasonal demand and helping fill needed route slots on long-haul flights to Europe, Latin America, Africa and the Middle East. In short, Atlanta concentrates the scale of cost advantages and connectivity of the airline’s entire network.
So What Is The Bottom Line?
At the end of the day, Atlanta is the world’s biggest international airport for good reason. Delta Air Lines has long been one of the most critical factors driving the airport’s growth, and there is little hiding around that statement.
Legacy airlines, like Delta, are typically catalysts for airport growth. Legacy carriers operate superconnector business models, meaning they generate cash flows by offering efficient connections between destinations worldwide.
Few airlines, however, have had as much of an impact on a single airport as Delta Air Lines has had on Atlanta Hartsfield-Jackson. As a result, the airport itself is a crucial linchpin not just in the airline’s global network, but in the global aviation industry as well.
